OMPJ

Valappil T Beena et al 10.5005/jp-journals-10037-1108 CASE REPORT

Ameloblastic Fibro- 1Valappil T Beena, 2Jasmin Jose, 3Sabu Paul, 4Manju S Mathunny, 5Sreela K Kottarathil, 6Shalu

ABSTRACT lesions with odontogenic epithelium with odontogenic 1 Introduction: Ameloblastic fibro-odontoma (AFO) is a rare ectomesenchyme, with or without hard tissue formation. benign, slow-growing, expansile epithelial AFO is a tumor with histological features similar to those with odontogenic ectomesenchyme. It constitutes about 1 to of ameloblastic fibroma (AF), but it shows inductive 3% of all odontogenic tumors. This lesion usually occurs in changes that lead to the formation of dentin or enamel. people less than 20 years old, and thus age is an important characteristic in the differential diagnosis. It may inhibit tooth eruption or displace involved teeth, although teeth in the affected area are vital.2-4 The lesions Case report: An 8-year-old boy reported with a swelling in the right mandibular region. Panoramic radiograph showed are usually diagnosed during the first and second decades a well-demarcated radiolucency containing radiopaque areas of life. Radiographically, the lesion presents with a well- of irregular shape extending from the right deciduous second circumscribed, unilocular or multilocular radiolucent molar to the permanent third molar region. A provisional clini- area containing various amounts of radiopaque material cal diagnosis of complex odontome was made. Ameloblastic fibro-odontoma, odontoameloblastoma, calcifying epithelial of irregular size and form. The large areas of calcification odontogenic tumor, and calcifying odontogenic cyst were also make it impossible to radiographically differentiate it included in the differential diagnoses. from complex odontoma.4,5,6 This article reports a case of Management and prognosis: Patient underwent tumor exci- AFO in an 8-year-old male with significant clinicoradio- sion, and histopathological examination confirmed as AFO. The graphic features, histopathology, differential diagnoses, patient was followed postoperatively for 12 months and no sign and treatment. of recurrence was noted. Conclusion: Long-term follow-up at regular short intervals CASE REPORT should be maintained in the management of AFO. Here we add one more case to the sparsely reported AFO with a brief An 8-year-old boy was referred to the outpatient depart- review of literature. ment at the Government Dental College, Kottayam, Keywords: Ameloblastic fibro-odontoma, Odontogenic tumors, Kerala, India, with a swelling in the right mandibular Odontoma. region. How to cite this article: Beena VT, Jose J, Paul S, Mathunny MS, There was no significant medical, social, or family Kottarathil SK, Shalu. Ameloblastic Fibro-odontoma. Oral history or history of local trauma or infection. Extraoral Maxillofac Pathol J 2017;8(2):94-97. examination showed mild facial asymmetry on the right Source of support: Nil side. On palpation, a hard painless swelling was observed in the right mandibular body. Intraoral examination Conflict of interest: None revealed a well-circumscribed swelling of the alveolar ridge, extending from the deciduous second molar to INTRODUCTION the anterior border of the ascending ramus, covered with Ameloblastic fibro-odontoma (AFO) is a rare benign, normal mucosa which was hard on palpation. The man- slow-growing, expansile epithelial odontogenic tumor dibular right permanent first molar was absent. with odontogenic ectomesenchyme. According to the Panoramic radiograph showed a large, well-demar- World Health Organization classification of odontogenic cated radiolucency containing tooth-like radiopaque tumors published in 2005, AFO belongs to the group of areas of irregular shape extending from the right decidu- ous second molar to the permanent third molar region. The tooth germ of the right lower permanent first molar was displaced to the base of the mandible by the lesion. 1Professor and Head, 2,5,6Postgraduate Student, 3Assistant Professor, 4Senior Lecturer The right lower permanent second and third molar tooth germs were involved by the mineralized mass (Fig. 1). 1-6Department of Oral Pathology and Microbiology, Government Dental College, Kottayam, Kerala, India Going by the clinical and radiographic findings, a provi- sional clinical diagnosis of complex odontome was made. Corresponding Author: Valappil T Beena, Professor and Head, Department of Oral Pathology and Microbiology Ameloblastic fibro-odontoma, odontoameloblastoma, Government Dental College, Kottayam, Kerala, India, Phone: calcifying epithelial odontogenic tumor, and calcifying +919847150407, e-mail: [email protected] odontogenic cyst were also included in the differential 94 OMPJ

Ameloblastic Fibro-odontoma

epithelium and loosely arranged spindle-shaped cells identical to stellate reticulum in the central area (Fig. 2). The ectomesenchymal component comprised loose connective tissue, with abundant extracellular matrix containing young, plump fibroblasts, sometimes with a stellate appearance, resembling the dental papilla. The decalcified sections showed enamel matrix and dentin-like substance (Fig. 3). In few areas, reduced enamel epithe- lium was observed around the matrix. The dental tissues were disorganized in some regions forming a large mass Fig. 1: Panoramic radiograph showing well-demarcated radiolucent of dentin around reduced enamel epithelium and enamel lesion affecting the right lower permanent molar region, containing matrix. No malignant changes were evident. Based on radiopaque areas of varying size, causing the displacement of the tooth germ of the lower first molar clinical and histopathological features, the tumor was diagnosed as AFO. No sign of recurrence was observed diagnoses. Under general anesthesia, by intraoral during a postoperative period of 12 months. approach, the tumor was excised. DISCUSSION Light microscopic examination of sections revealed strands and islands of odontogenic epithelium showing The present case meets the clinicopathological criteria for peripheral palisading columnar cells resembling enamel the diagnosis of AFO, which is a rare mixed odontogenic

A B Figs 2A and B: Strands and islands of odontogenic epithelium showing peripheral palisading and loosely arranged central stellate reticulum-like cells embedded in myxoid cell-rich stroma resembling the dental papilla: (A) (hematoxylin and eosin [H&E] 100×); and (B) (H&E 400×)

A B Figs 3A and B: Photomicrograph of the decalcified sections showing dentin-like material and enamel matrix around reduced enamel epithelium (A) (hematoxylin and eosin [H&E] 100×); (B) (H&E 400×) Oral and Maxillofacial Pathology Journal, July-December 2017;8(2):94-97 95 Valappil T Beena et al tumor. The AFO accounts for 1 to 3% of all odontogenic that different lesions are being described under the same tumors.5 The tumor has equal distribution in the maxilla term of AFO, where some are hamartomatous in nature and mandible and shows predilection to the molar region. and others a true de novo neoplasm. Currently, it is not There is no gender variance and mean age of subjects is possible to distinguish a hamartoma from a neoplasm 11.5 years. Slootweg7 reviewed 50 patients with this lesion, only based on histological features. A small lesion on for whom the mean age was 8.1 years. This lesion usually the occlusal surface of an unerupted molar may be the occurs in people less than 20 years old, and thus age is immature stage of an odontoma, whereas a lesion that an important characteristic in the differential diagnosis. causes swelling and cortical expansion is likely to be a The two frequent patient complaints are failure of true AFO.14 tooth eruption and swelling. Asymptomatic cases are inci- Immunohistochemistry reveals that all epithelial dentally detected on radiography. This lesion is generally components in the AF-like area showed expression of considered a slow-growing central jaw tumor; however, CK8, CK13, CK16, CK14, CK18, and CK19, and coex- several exceptions to this pattern have been reported.5 pression of these cytokeratins and vimentin. Miyauchi Radiographs reveal a well-defined radiolucent area et al14 suggest that the epithelial component showed cell enclosing varying amount of radiopaque material of differentiation of the with the potential for irregular size and shape.8 The ratio of radiolucent to epithelial–mesenchymal induction. The cell kinetics in radiopaque areas ranges from one lesion to another. Some mandibular AFO was studied by bromo-deoxyuridine of the lesions are relatively small when first detected, and proliferating cell nuclear antigen. The result of measuring 1 to 2 cm in diameter, whereas others may be immunohistochemical investigations suggested that the exceedingly large, involving a considerable portion of the mesenchymal component was more proliferative than the body of the mandible or maxilla.7 epithelial component.15 Such an immunohistochemical Histologically, AFO is composed of cords, strands, investigation may be useful in evaluating the proliferative and islands of odontogenic epithelium within a cellular potential of odontogenic tumors. primitive ectomesenchyme that simulates dental papilla. Slootweg16 compared ultrastructure of the epithelial– Dentin and enamel matrix are also seen.9 Conversely, the mesenchymal interface of AFOs with that of the nor- elite presence of dentin depicts another entity, amelo- mally developing tooth germ and it was noted that blastic fibrodentinoma. The histogenesis of this tumor the ultrastructure of the tumors was identical with the is debatable. Ameloblastic fibro-odontoma is a benign normally developing odontogenic tissues up to but not tumor that exhibits the same benign biologic behavior including the differentiation of mesenchymal cells into as that of AF, showing inductive changes that lead to the tall columnar odontoblasts. The absence of odontoblasts formation of both dentin and enamel. The presence of in the AFOs resulted in an absence of tubular dentin both dentin and enamel is imperative to differentiate AFO in place of which a homogeneous collagen-containing from AF, which is devoid of tooth differentiation.10 It has material was synthesized. Failure of the mesenchymal been a matter of dispute whether the mixed odontogenic cells to transform into tall columnar odontoblasts could tumors (AFO, AF, and ) should be classified be due to the lack of the normally occurring induction as separate entities or if they represent different stages of of the ectomesenchyme by the odontogenic epithelium development of a single entity. Ameloblastic fibroma, the according to Slootweg. tumor with least differentiation, was considered to have When AFO presents with the typical age, location, and progressed into a moderately differentiated form, AFO, radiographic pattern, the diagnosis is usually obvious. and finally into complex odontoma. But, this concept of The differential diagnosis should include lesions with “continuum of differentiation” is not widely accepted, mixed radiographic patterns, such as calcifying epithelial and many authors consider these lesions as separate odontogenic cyst, calcifying odontogenic tumor, immature pathologic entities.7,11 Many of the patients who are complex odontoma, odontoameloblastoma, and adenoma- affected by AF are generally older than those affected toid odontogenic tumor. Ameloblastic fibro-odontoma can by AFO, although various studies suggest that AFOs be differentiated from calcifying odontogenic cyst on the are hamartomatous in nature, representing a stage that basis that it is a well-circumscribed, solid or cystic lesion precedes the complex odontoma.12 It seems that not all derived from odontogenic epithelium that microscopically cases of AFO should be considered as hamartomatous, resembles but differs by containing ghost since there are cases that show true neoplastic behavior cells and spherical calcifications. Calcifying epithelial and because there is evident existence of a malignant odontogenic tumor comprises sheets of polyhedral tumor variant of the disease.4,13 Furthermore, the recurrences cells along with homogeneous eosinophilic deposits that in AFO denote its neoplastic nature.7 Thus, it is possible stain positive for amyloid, and spherical calcifications

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Ameloblastic Fibro-odontoma which discriminate it from AFO. The term odontoam- 5. Chang H, Shimizu MS, Precious DS. Ameloblastic fibro- eloblastoma refers to tumors representing a histological odontoma: a case report. J Can Dent Assoc 2002 Apr;68(4): 243-246. combination of ameloblastoma and complex odontoma, 6. Bernhoft CH, Bang G, Gilhuss-Moe O. Ameloblastic which will behave in the invasive manner of classic fibroodontoma. Int J Oral Surg 1979 Jun;8(3):241-244. ameloblastoma. It is usually an unencapsulated lesion 7. Slootweg PJ. An analysis of the interrelationship of the mixed and shows ameloblastic areas and ghost cells which odontogenic tumors – ameloblastic fibroma, ameloblastic help in the differential diagnosis. Ameloblastic fibro- fibro-odontoma, and the odontoma. Oral Surg Oral Med Oral odontoma may not be histologically differentiated Pathol 1981 Mar;51(3):266-276. 8. Daley DT, Wysocki GP, Pringle GA. Relative incidence of from an immature complex odontoma. Ameloblastic odontogenic tumors and oral and jaw cysts in a Canadian fibro-odontoma is well encapsulated and there is little population. Oral Surg Oral Med Oral Pathol 1994 Mar;77(3): propensity for local invasion, so the treatment approach 276-280. is primarily conservative surgery. In the present case, 9. Furst I, Pharoah M, Phillips J. Recurrence of an ameloblastic no recurrence was observed after excision of the lesion fibro-odontoma in a 9-year-old boy. J Oral Maxillofac Surg 1999 May;57(5):620-623. and preservation of the first molar. Tissue healing was 10. Friedrich RE, Siegert J, Donath K, Jäkel KT. Recurrent amelo- adequate, even without placement of bone graft or blastic fibro-odontoma in a 10-year-old boy. J Oral Maxillofac replacement material. Surg 2001 Nov;59(11):1362-1366. 11. Eversole RE, Tomich CE, Cherrick HM. Histogenesis of CONCLUSION odontogenic tumor. Oral Surg Oral Med Oral Pathol 1971 Oct;32(4):569-581. As discussed earlier, AFO with a neoplastic nature has a 12. Chen Y, Li TJ, Gao Y, Yu SF. Ameloblastic fibroma and potential for recurrence. related lesions: a clinicopathologic study with reference to their nature and interrelationship. J Oral Pathol Med 2005 Nov;34(10):588-595. REFERENCES 13. Howell RM, Burkes EJ Jr. Malignant transformation of amelo- 1. Barnes, L.; Eveson, JW.; Reichart, P.; Sidransky, D. Pathology blastic fibro-odontoma to ameloblastic fibrosarcoma. Oral and genetics. Head and neck tumors. In: Kleihues P, Sobin LH, Surg Oral Med Oral Pathol 1977 Mar;43(3):391-401. editors. World Health Organization Classification of Tumours. 14. Miyauchi M, Takata T, Ogawa I, Ito H, Nikai H, Ijuhin N, Lyon: IARC Press; 2005. Tanimoto K, Miyauchi S. Immunohistochemical observations 2. Hutt PH. Ameloblastic fibro-odontoma: report of a case with on a possible ameloblastic fibroodontoma. J Oral Pathol Med documented four-year follow-up. J Oral Maxillofac Surg 1982 1996 Feb;25(2):93-96. Jan;40(1):45-48. 15. Sekine J, Kitamura A, Ueno K, Sano K, Inokuchi T, Takahashi H, 3. Philipsen HP, Thosaporn W, Reichart PA, Grundt G. Okabe H. Cell kinetics in mandibular ameloblastic fibroodon- Odontogenic lesions in opercular of permanent molars toma evaluated by bromodeoxyuridine and proliferating cell delayed in eruption. J Oral Pathol Med 1992 Jan;21(1): nuclear antigen immune histochemistry: case report. Br J Oral 38-41. Maxilofac Surg 1996 Oct;34(5):450-453. 4. Miller AS, López CF, Pullon PA, Elzay RP. Ameloblastic 16. Slootweg PJ. Epithelio-mesenchymal morphology in amelo- fibroodontoma: report of seven cases. Oral Surg Oral Med blastic fibroodontoma: a light and electron microscopic study. Oral Pathol 1976 Mar;41(3):354-365. J Oral Pathol 1980 Jan;9(1):29-40.

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